Operator Precedence in C++

C++ Operators – Part 9

Forward: In this article we look at operator precedence in C++.

By: Chrysanthus Date Published: 24 Aug 2012

Introduction

This is part 9 of my series, C++ Operators. It is possible to have a statement with many operators. The question is, which operator is executed first? Some operators will always be executed first before others. In fact there are different levels of this, and that is operator precedence. In this article we look at operator precedence in C++.

Note: If you cannot see the code or if you think anything is missing (broken link, image absent), just contact me at forchatrans@yahoo.com. That is, contact me for the slightest problem you have about what you are reading.

Example
Consider the following statement:

int x = 2 + 8 % 5;

There are three operators here, which are =, + and %. Now = is of a very low precedence and it is executed last. The question then is between + and %; which is executed first? If the modulus operator, % is executed first, the answer will be 5. If the Addition operator is executed first, the answer will be 0. Well, in C++, % is of a higher precedence than +, so % is executed first and the answer is 5. You can force the + to be executed first by using brackets, as follows:

int x = (2 + 8) % 5;

Whenever you are in doubts of which operator would be executed first, use brackets, to be sure that an operator would be executed first. Brackets can be nested.

Precedence Order

I now give you the precedence order for the operators we have seen in this series. This list has majority of C++ operators. The highest precedence is given first, that is followed by the second, then third, and so on, until the last.

Scope Operator
::
Grouping (direction of operation): Left-to-right

Postfix Operators
() [] . -> ++ -- dynamic_cast static_cast reinterpret_cast const_cast typeid
Grouping: Left-to-right

Unary Prefix Operators
++ -- ~ ! sizeof new delete
Grouping: Right-to-left

Reference and Indirection Operators
& *
Grouping: Right-to-left

Unary Sign Operators
+ -
Grouping: Right-to-left

Type Casting Operators
(type)
Grouping: Right-to-left

Pointer-to-member Operators
.* ->*
Grouping: Left-to-right

Multiplicative Operators
% * /
Grouping: Left-to-right

Additive Operators
+ -
Grouping: Left-to-right

Bitwise Shift Operators
<< >>
Grouping: Left-to-right

Relational Operators
< > <= >=
Grouping: Left-to-right

Equality Operators
== !=
Grouping: Left-to-right

Bitwise AND Operator
&
Grouping: Left-to-right

Bitwise XOR Operator
^
Grouping: Left-to-right

Bitwise OR Operator
|
Grouping: Left-to-right

Logical AND Operator
&&
Grouping: Left-to-right

Logical OR Operator
||
Grouping: Left-to-right

Conditional Operator
?:
Grouping: Right-to-left

Assignment Operators
= *= /= %= += -= >>= <<= &= ^= !=
Grouping: Right-to-left

Comma Operator
,
Grouping: Left-to-right

Well, we have seen a lot in this series. We should really take a break here. We continue in the next part.

Chrys

Broad Network

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Operator Precedence in C++

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